include/linux/timekeeper_internal.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * You SHOULD NOT be including this unless you're vsyscall
   4  * handling code or timekeeping internal code!
   5  */
   6
   7 #ifndef _LINUX_TIMEKEEPER_INTERNAL_H
   8 #define _LINUX_TIMEKEEPER_INTERNAL_H
   9
  10 #include <linux/clocksource.h>
  11 #include <linux/jiffies.h>
  12 #include <linux/time.h>
  13
  14 /**
  15  * struct tk_read_base - base structure for timekeeping readout
  16  * @clock:      Current clocksource used for timekeeping.
  17  * @mask:       Bitmask for two's complement subtraction of non 64bit clocks
  18  * @cycle_last: @clock cycle value at last update
  19  * @mult:       (NTP adjusted) multiplier for scaled math conversion
  20  * @shift:      Shift value for scaled math conversion
  21  * @xtime_nsec: Shifted (fractional) nano seconds offset for readout
  22  * @base:       ktime_t (nanoseconds) base time for readout
  23  * @base_real:  Nanoseconds base value for clock REALTIME readout
  24  *
  25  * This struct has size 56 byte on 64 bit. Together with a seqcount it
  26  * occupies a single 64byte cache line.
  27  *
  28  * The struct is separate from struct timekeeper as it is also used
  29  * for a fast NMI safe accessors.
  30  *
  31  * @base_real is for the fast NMI safe accessor to allow reading clock
  32  * realtime from any context.
  33  */
  34 struct tk_read_base {
  35         struct clocksource      *clock;
  36         u64                     mask;
  37         u64                     cycle_last;
  38         u32                     mult;
  39         u32                     shift;
  40         u64                     xtime_nsec;
  41         ktime_t                 base;
  42         u64                     base_real;
  43 };
  44
  45 /**
  46  * struct timekeeper - Structure holding internal timekeeping values.
  47  * @tkr_mono:           The readout base structure for CLOCK_MONOTONIC
  48  * @tkr_raw:            The readout base structure for CLOCK_MONOTONIC_RAW
  49  * @xtime_sec:          Current CLOCK_REALTIME time in seconds
  50  * @ktime_sec:          Current CLOCK_MONOTONIC time in seconds
  51  * @wall_to_monotonic:  CLOCK_REALTIME to CLOCK_MONOTONIC offset
  52  * @offs_real:          Offset clock monotonic -> clock realtime
  53  * @offs_boot:          Offset clock monotonic -> clock boottime
  54  * @offs_tai:           Offset clock monotonic -> clock tai
  55  * @tai_offset:         The current UTC to TAI offset in seconds
  56  * @clock_was_set_seq:  The sequence number of clock was set events
  57  * @cs_was_changed_seq: The sequence number of clocksource change events
  58  * @next_leap_ktime:    CLOCK_MONOTONIC time value of a pending leap-second
  59  * @raw_sec:            CLOCK_MONOTONIC_RAW  time in seconds
  60  * @cycle_interval:     Number of clock cycles in one NTP interval
  61  * @xtime_interval:     Number of clock shifted nano seconds in one NTP
  62  *                      interval.
  63  * @xtime_remainder:    Shifted nano seconds left over when rounding
  64  *                      @cycle_interval
  65  * @raw_interval:       Shifted raw nano seconds accumulated per NTP interval.
  66  * @ntp_error:          Difference between accumulated time and NTP time in ntp
  67  *                      shifted nano seconds.
  68  * @ntp_error_shift:    Shift conversion between clock shifted nano seconds and
  69  *                      ntp shifted nano seconds.
  70  * @last_warning:       Warning ratelimiter (DEBUG_TIMEKEEPING)
  71  * @underflow_seen:     Underflow warning flag (DEBUG_TIMEKEEPING)
  72  * @overflow_seen:      Overflow warning flag (DEBUG_TIMEKEEPING)
  73  *
  74  * Note: For timespec(64) based interfaces wall_to_monotonic is what
  75  * we need to add to xtime (or xtime corrected for sub jiffie times)
  76  * to get to monotonic time.  Monotonic is pegged at zero at system
  77  * boot time, so wall_to_monotonic will be negative, however, we will
  78  * ALWAYS keep the tv_nsec part positive so we can use the usual
  79  * normalization.
  80  *
  81  * wall_to_monotonic is moved after resume from suspend for the
  82  * monotonic time not to jump. We need to add total_sleep_time to
  83  * wall_to_monotonic to get the real boot based time offset.
  84  *
  85  * wall_to_monotonic is no longer the boot time, getboottime must be
  86  * used instead.
  87  */
  88 struct timekeeper {
  89         struct tk_read_base     tkr_mono;
  90         struct tk_read_base     tkr_raw;
  91         u64                     xtime_sec;
  92         unsigned long           ktime_sec;
  93         struct timespec64       wall_to_monotonic;
  94         ktime_t                 offs_real;
  95         ktime_t                 offs_boot;
  96         ktime_t                 offs_tai;
  97         s32                     tai_offset;
  98         unsigned int            clock_was_set_seq;
  99         u8                      cs_was_changed_seq;
 100         ktime_t                 next_leap_ktime;
 101         u64                     raw_sec;
 102
 103         /* The following members are for timekeeping internal use */
 104         u64                     cycle_interval;
 105         u64                     xtime_interval;
 106         s64                     xtime_remainder;
 107         u64                     raw_interval;
 108         /* The ntp_tick_length() value currently being used.
 109          * This cached copy ensures we consistently apply the tick
 110          * length for an entire tick, as ntp_tick_length may change
 111          * mid-tick, and we don't want to apply that new value to
 112          * the tick in progress.
 113          */
 114         u64                     ntp_tick;
 115         /* Difference between accumulated time and NTP time in ntp
 116          * shifted nano seconds. */
 117         s64                     ntp_error;
 118         u32                     ntp_error_shift;
 119         u32                     ntp_err_mult;
 120 #ifdef CONFIG_DEBUG_TIMEKEEPING
 121         long                    last_warning;
 122         /*
 123          * These simple flag variables are managed
 124          * without locks, which is racy, but they are
 125          * ok since we don't really care about being
 126          * super precise about how many events were
 127          * seen, just that a problem was observed.
 128          */
 129         int                     underflow_seen;
 130         int                     overflow_seen;
 131 #endif
 132 };
 133
 134 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 135
 136 extern void update_vsyscall(struct timekeeper *tk);
 137 extern void update_vsyscall_tz(void);
 138
 139 #else
 140
 141 static inline void update_vsyscall(struct timekeeper *tk)
 142 {
 143 }
 144 static inline void update_vsyscall_tz(void)
 145 {
 146 }
 147 #endif
 148
 149 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */